Answer:
B: It was a compound
Step-by-step explanation:
If a chemical reaction was used to separate a sample into its components, then it was a compound. For example, water (H2O, a compound) can be separated by electrolysis into oxygen and hydrogen (its components). the chemical reaction is:
2 H2O -> O2 + 2 H2
Heterogeneous and homogeneous mixtures can be separated by physical ways. Pure substance can be either a compound or an element, so this option is not specific enough to be the correct answer.